JPS63196446A - Movie photographing device - Google Patents

Abstract

PURPOSE:To make the rise-up characteristic of a motor up to a desired speed approximate to a linear line by providing a control means for controlling the rotational speed of the motor in accordance with the output of an output means and the output of a detecting means. CONSTITUTION:An MPU (micro processing unit) 14 selects one of programs stored in a memory circuit 15 in accordance with a set speed inputted in the MPU 14 from an input and output circuit 5, and therefore steppedly changes over speed instructions until the speed of a motor reaches the set speed, the speed instructions being transmitted to a speed control circuit 6 through the input and output circuit 5. The speed control circuit 6 drives the motor 2 by means of a drive circuit 7, and detect the rotational speed omegaps by means of a rotary encoder 8 and a photo sensor 9 so that the rotational speed of the motor 2 is controlled so as to coincide with an instructed speed. In this arrangement, the MPU 14 selects an optimum one of the rise up programs in accordance with data concerning the diameter of the wound-up film on a spool 10 after completion of wind-up, that is, the amount of the wind-up and the set speed, and delivers a speed instruction to the speed control circuit 6 in accordance under instructions of the program.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motion picture photographing apparatus that drives a roll film using an electric motor.

[Prior Art] Conventionally, cine cameras have been used to take X-ray images of fast-moving objects such as the heart using a contrast agent. Most of the cine cameras currently on the market are capable of shooting at a low speed of 10 frames per second to a high speed of 150 frames per second.The film drive system of a normal cine camera is as follows:
At the aperture for photographing, the film is intermittently fed by a feeding claw according to a set speed in the order of feeding, stopping, and feeding, and the winding shaft on the winding side always winds up a fixed amount of film continuously. Usually, the winding shaft is driven by an electric motor via a gear belt, similar to the feed pawl for intermittent feeding. However, when winding a fixed amount of film, the winding speed changes depending on the size of the winding diameter. Therefore, the winding shaft, which is driven by an electric motor rotating at a constant speed, absorbs changes in speed due to changes in its diameter by slipping the shaft.

On the other hand, the start-up characteristics of the motor are uniquely determined by the characteristics of the motor, the capacity of the power supply applied to the motor, the characteristics of the servo circuit, the load, etc. That is, the electric motor accelerates from a zero speed state toward the set speed as shown in FIG. 4, and converges to the set speed while overshooting.

In the conventional example described above, when winding a long film of 600 feet such as cine film, the set speed is 2 per second.
There is no problem when the take-up diameter is small and the take-up diameter is small, such as 5 frames. However, when the take-up diameter becomes large and you try to start up at a high speed of 150 frames per second, the inertia of the film is large and there is no problem at the start. The winding shaft slips, causing a delay in winding the film sent out by the feed claw, and causing the winding shaft to temporarily swell.

This makes film feeding unstable, and in the worst case, jamming occurs and feeding becomes impossible. On the other hand, if the slip torque is increased in order to eliminate slip, there is a risk that strong tension will be applied to the film and the film will be cut.

[Object of the Invention] An object of the present invention is to make the start-up characteristic of the motor closer to a straight line by controlling the start-up characteristic of the electric motor until it reaches the target speed from zero speed to the target speed, and to increase the slip torque at the time of high-speed start-up. To provide a motion picture photographing device which has a drive system that smoothly starts up without causing a winding failure even when the winding is not performed, and has an optimum start-up characteristic according to changes in set speed and winding diameter.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a motion picture photographing apparatus that drives a roll film by an electric motor.
An output means for outputting a set speed of the electric motor, a detection means for detecting the winding amount of the roll film, and a control means for controlling the rotational speed of the electric motor based on the output of the output means and the output of the detection means. A movie shooting apparatus characterized in that the control means controls the speed of the electric motor to reach a set speed by varying its output.

[Embodiments of the Invention] The present invention will be described in detail below based on embodiments illustrated in FIGS. 1 to 3.

FIG. 1 is a block circuit configuration diagram. 1 is a film feeding system of a cine camera, and the film F is intermittently fed by a feeding pawl 3 driven by an electric motor 2, and wound by a winding shaft 4. ing. Electric @ 2 operates speed control circuit 6 and drive circuit 7 according to the speed command from input/output circuit 5.
The rotational speed ωps is detected by a rotary encoder 8 attached to the motor shaft 6 and a photosensor 9 opposed to the rotary encoder 8, and is fed back to the speed control circuit 6. On the other hand, a film diameter detection lever 11 extending from a potentiometer 10 is brought into contact with the winding shaft 4, and the output of the potentiometer 10 is inputted via a resistance voltage conversion circuit 12 and an A/D converter 13. It is connected to the output circuit 5. The input/output circuit 5 is MP
The MPU 14 is connected to a microprocessing unit (U) 14, and the MPU 14 is further connected to a memory circuit 15.

The MPU 14 selects a program stored in the memory circuit 15 based on the set speed input from the input/output circuit 5 to the MPU 14, changes the speed command step by step until the target set speed is reached, and then sends the command via the input/output circuit 5. A speed command is output to the speed control circuit 6.

The speed control circuit 6 drives the electric motor 2 via the drive circuit 7, and detects the rotation speed ωps of the electric motor 2 using a rotary encoder 8 and a photo sensor 9 attached to the electric motor 2, so that the rotation speed of the electric motor 2 becomes the speed command. control to match. The film F is fed in a fixed amount per unit time by a feed claw 3 driven by an electric motor 2, and is wound up by a take-up shaft 4.The take-up shaft 4 is connected to the electric motor 2 via gears, belts, etc. In order to adjust the rotational speed of the winding shaft 10 depending on the difference in winding diameter, the winding shaft 10 is driven via a slip mechanism (not shown).

Detection lever 11 for detecting the diameter of the wound film
The angle of
14.

The MPU 14 is the winding shaft 10 of this wound film F.
An optimal start-up program is selected based on the diameter information, that is, the winding amount, and the set speed, and a speed command is output to the speed control circuit 6 in accordance with this program.

FIG. 2 is a block circuit diagram of the speed control circuit 6.
The speed command signal from the input/output circuit 5 is sent to the reference signal generator 16.
The output ω0 of the reference signal generator 16 is connected to an F/V converter 17 that converts frequency into voltage and a U terminal of a U/D counter 18. In addition, the photo sensor 9
Similarly, the rotational speed ωps obtained in the F/V converter 17, U
/D is connected to the D terminal of the counter 18. The output of the F/V converter 17 is connected to an adder 20 via an amplifier 19, and the output of the U/D counter 18 is connected to a D/A converter 21. It is connected to an adder 20 via an amplifier 22, and the output of the adder 20 is connected to a drive circuit 7 via an amplifier 23.

The reference signal generator 16 outputs a frequency fO determined by the following equation based on the speed command ω0 output from the MPU 14.

(1) 0 = 2π*fO=2π*NsfM (however, N
is the number of gratings of the rotary encoder 8, f is the target rotational speed of the electric motor 2 [H4F], and the F/V converter 17 generates the speed error ω0-ωps (ωps=2π・fps=2π) through the amplifier 22 with a gain of G.
・N red fm: However, fm is the speed of electric motor 2 [H, z]
) is output. U/D counter 15, A/D converter 17
The output of is the integral value of the speed error through an amplifier 19 with a gain of K! (ω0-ωps) dt is output. Adder 20 calculates (ω0-ωps) and f (ω0-ωps)
dt and outputs an error signal to the drive circuit 7 through an amplifier 23 having a gain of A.

When the rotation speed ωps of the electric motor 2 becomes ω0, the error is O
Therefore, it will rotate at a constant speed.

Therefore, by switching the speed command ωO from low speed to several speeds, the electric motor 2 always accelerates toward the speed command 00, so that its rise follows a predetermined program.

In the above embodiment, the rise control is performed in stages, but by making the speed command ω0 more fine, the motor 2
It becomes possible to control the rise in a substantially linear manner.

[Effects of the Invention] As explained above, according to the movie shooting apparatus according to the present invention, the start-up program of the electric motor is selected depending on the amount of film to be wound, and the start-up of the electric motor is controlled in stages, thereby adjusting the film diameter. Even if there is a large variation in inertia between small and large values, it is possible to control the start-up of the motor while taking into account the variation in inertia, and the slip of the winding shaft can be minimized without increasing the winding re-slip torque. This allows for stable film feeding with a smooth start-up. In addition, the tension applied to the film can be kept low to eliminate sudden speed changes at the time of start-up, and the load applied to mechanical gears and the like can also be reduced.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of a movie shooting apparatus according to the present invention, in which Figure 1 is a block circuit diagram, Figure 2 is a block circuit diagram of a speed control section, and Figure 3 is a block circuit diagram of a speed control section. FIG. 4 is a diagram showing the startup characteristics of the motor when startup control is performed, and FIG. 4 is a diagram showing the startup characteristics of the motor when conventional startup control is not performed. 1 is the film feeding system, 2 is the electric motor, 3 is the feeding claw, 4
is a winding shaft, 5 is an input/output circuit, 6 is a speed control circuit, 7 is a drive circuit, 8 is a rotary encoder, 9 is a photosensor,
10 is a potentiometer, 11 is a film diameter detection lever, 12 is a resistance/voltage conversion circuit, 13 is an A/D converter,
14 is an MPU, 15 is a memory circuit, 16 is a reference signal generator, 17 is an F/V converter, 18 is a U/D counter, 19
is an adder, and 21 is a D/A converter.

Claims (1)

[Scope of Claims] 1. A movie shooting apparatus that drives a roll film by an electric motor, comprising: an output means for outputting a set speed of the electric motor; a detection means for detecting the winding amount of the roll film; and control means for controlling the rotational speed of the electric motor based on the output and the output of the detection means, and the control means controls the speed of the electric motor to reach a set speed by varying the output. A movie shooting device characterized by: 2. The movie shooting apparatus according to claim 1, wherein the output of the output means is performed by a start-up program that controls the start-up of rotation of the electric motor.